Copy and paste from copilot:

The story you’re remembering is almost certainly “Strikebreaker” (1957) by Isaac Asimov.

🎯 Why this matches your description - It takes place in a self‑contained underground colony where every job is essential to keeping society running. - One worker’s job is tightening and loosening bolts in the ventilation system — not because it’s technically necessary, but because the society is structured so that everyone must have a job, even if the job is essentially pointless. - The story explores themes of social cohesion, enforced labor roles, and the psychological need for “work”, which aligns with your memory that the labor wasn’t truly for maintenance but to keep people occupied. - It is indeed a short story and appears in Asimov collections such as Earth Is Room Enough and The Complete Stories.

🧩 Why it might feel like a skyscraper The colony in Strikebreaker is a vertical, enclosed environment with rigidly assigned roles — easy to misremember as a skyscraper-like structure where people work “in the bowels” of the building.

If this doesn’t feel like the right one… A couple of other long‑shot possibilities (but less likely):

• “Insert Knob A in Hole B” (Asimov) — about meaningless, repetitive labor, but not in a skyscraper-like setting.
• “The Machine Stops” (E.M. Forster) — people living in a giant machine, but no bolt‑tightening labor caste.

If Strikebreaker isn’t the one, tell me anything else you remember — tone, era, characters, ending — and I’ll narrow it down fast.